A variety of elastomeric materials are used as components found in the engine compartment of a vehicle. High temperatures generated by many internal combustion engines have adversely affected the elastomeric materials, such as those used in spark plug boots, ignition wires, engine gaskets and the like. Such temperatures often exceed 500.degree. F. and, with time, cause the elastomeric materials to become brittle, cracked and worn. In the area of spark plug boots, such wear reduces the effectiveness of the boot seal in maintaining and protecting the spark plug and its electrical connection to the ignition wire. Various devices and methods have been introduced to protect such elastomeric components.
To provide spark plug boot protection in such high temperature environments, a variety of expensive and custom made heat shields have been used. U.S. Pat. No. 4,671,586, issued Jun. 9, 1987 to DeBolt, shows a spark plug shield and boot assembly which includes a heat shield formed in the shape of a thin walled cylindrical shell of aluminum or other lightweight metal which peripherally surrounds the elastomeric boot. U.S. Pat. No. 3,881,051, issued Apr. 29, 1975 to Berry, shows a spark plug boot formed of silicone rubber and having a metal screen integrally molded therein, the screen extending through one end of the boot and into engagement with the spark plug shell to provide an electrical ground for the screen. While such shields are generally effective for their intended purpose, they are costly and fail to meet the goals of improved installation, operation and serviceability.
U.S. Pat. No. 5,063,012, issued Nov. 5, 1991 to Gibbon (Gibbon '012), shows an elastomeric component sprayed with a heat resistant, heat reflecting resin-based paint. While the elastomeric component itself is capable of withstanding the degrading effects of heat, the paint is less than optimally flexible.
The Gibbon '012 composition used a resin-based paint made from SR125. SR125 is a silicone resin made using the monomers dimethyl dichlorosilane and methyl trichlorosilane. This coating is relatively inflexible and permits little elongation of the painted component. Stretching a spark plug boot painted with a resin-based paint, to install an ignition cable, may cause the paint to develop cracks, resulting in the paint tending to flake off. Consequently, an unpainted portion of the elastomeric component may be left exposed to the surrounding environment.
In view of the prior art attempts, a long felt need continues to exist for a heat-reflective paint which, when dried, resists cracking and provides good adhesion and improved flexibility, even under high temperature conditions.